Note, though, there's still no confirmation of how many episodes are in either series 8 or 9's "full runs" - just that they won't be split seasons.
Moffat calls it "the traditional form," which implies 13 episodes and a Christmas special.
So what? 28 episodes in the next two series?
I just dont see any where near that many happening. Certainly not in any type of timely manner.
Maybe if season 8 runs end of 2014 into start of 2015 and season 9 happens in 2016.
Why not?
If it starts to air late August, i.e. Bank Holiday Weekend which would mean an air date of 23-8-14. That gives you at least seven months to film, you can do the FX works during that time period and you've still got time to to the last few episodes FX work whilst the earlier episodes are airing. Repeat in 2015.